Aluminum alloy material

ABSTRACT

An aluminum alloy material contains Mg: 7.0% to 10.0% (% by mass, the same applies hereinafter) and Ca: not more than 0.1%, and the aluminum alloy material contains a remainder constituted by aluminum and an inevitable impurity. The aluminum alloy material has a tensile strength of not less than 300 MPa and less than 500 MPa and an elongation of not less than 20%.

TECHNICAL FIELD

The present invention relates to a high-strength aluminum alloy materialhaving reduced strength anisotropy.

BACKGROUND ART

Recently, there has been a demand for using an aluminum alloy materialto make stronger and lighter various products including, for example, ahousing of an electrical device. Using an aluminum alloy material havinghigher strength makes it possible to reduce the amount of usage of thealuminum alloy material while maintaining the strength of the productsat the same degree as before, and thus enables reduction in the weightsof the products.

Typical high-strength aluminum alloys include, for example, a 6000series alloy and a 7000 series alloy. However, the above-describedalloys are heat-treatable alloys, which require solution treatment andaging heat treatment, and thus have a problem of low productionefficiency. In addition, the 7000 series alloy contains Zn and Cu in alarge amount, and thus have a problem of causing corrosion to easilyoccur depending on usage environments.

In view of the above, non-heat-treatable aluminum alloys are used insome cases. Typical non-heat-treatable aluminum alloys include a 5000series alloy, which has the highest strength. The 5000 series alloy,which typically has excellent corrosion resistance, does not require thesolution treatment and the aging heat treatment, so that the 5000 seriesalloy is produced with high efficiency. Further, increase in the amountof an element added to the 5000 series alloy makes it possible toachieve the 5000 series alloy having strength not less than that of a6000 series alloy. For the above reasons, proposed is a 5000 seriesaluminum alloy material containing not less than 5% by weight of Mg,which is a major additive element (see Patent Literatures 1 to 3).

CITATION LIST Patent Literature [Patent Literature 1]

Japanese Patent Application Publication, Tokukai, No. 2007-186747

[Patent Literature 2]

Japanese Patent Application Publication, Tokukai, No. 2001-98338

[Patent Literature 3]

Japanese Patent Application Publication, Tokukaihei, No. 7-197170

SUMMARY OF INVENTION Technical Problem

The contents of Mg in the aluminum alloy materials described in theabove Patent Literatures 1 to 3 are increased to an amount of not lessthan 5% by weight to make the aluminum alloy material stronger. However,Patent Literatures 1 to 3 do not give any consideration to strengthanisotropy of the aluminum alloy materials.

In a case where an aluminum alloy material has high strength anisotropy,an end product has low rigidity in a particular direction, so that thereliability of the end product could decrease. In addition, failure indimension accuracy or other accuracy could occur in a production processsuch as press forming. In particular, an aluminum alloy material (Otempered material) which has been annealed is required to have highformability, and therefore, the O tempered material having high strengthanisotropy could lead to the occurrence of cracking in a press formingprocess.

It is an object of an aspect of the present invention, which has beenmade to solve the above problem, to provide an aluminum alloy materialwhich has both high strength and reduced strength anisotropy, bycontrolling the metal structure.

Solution to Problem

To solve the above problems, an aluminum alloy material in accordancewith an aspect of the present invention contains Mg: 7.0% to 10.0% (% bymass, the same applies hereinafter) and Ca: not more than 0.1%, thealuminum alloy material containing a remainder constituted by aluminumand an inevitable impurity, the aluminum alloy material having a tensilestrength of not less than 300 MPa and less than 500 MPa and anelongation of not less than 20%.

Advantageous Effects of Invention

An aspect of the present invention makes it possible to produce analuminum alloy material which has both high strength and reducedstrength anisotropy.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating measurement directions of tensilestrengths of an aluminum alloy material in the present embodiment.

DESCRIPTION OF EMBODIMENTS

The inventors of the present invention diligently investigated andstudied alloy composition and metal structure which enable reduction inthe strength anisotropy of a high-strength aluminum alloy materialcontaining Mg (magnesium) in a large amount. The inventors eventuallyfound that it is possible to reduce the strength anisotropy bycontrolling an appropriate metal structure through adjustments to thealloy composition and to a production process.

The following description will discuss an aluminum alloy material inaccordance with an embodiment of the present invention in detail. Notethat it is assumed that the aluminum alloy material of the presentembodiment is used for members of household electrical appliances,buildings, structures, transport equipment, and the like that arerequired to have strength and isotropy of strength. In the followingdescription, the unit “% by mass” is abbreviated and written simply as“%”.

(Elements Which Must Be Contained in Aluminum Alloy)

[Mg]

Mg (magnesium) is present mainly in the form of a solid solutionelement, and has an effect of improving strength. The content of Mg inthe aluminum alloy being not less than 7.0% makes it possible tosufficiently obtain the effect of improving strength.

However, the content of Mg in the aluminum alloy exceeding 10.0% causesoccurrence of cracking during hot rolling, and thus could lead todifficulty in production. Accordingly, the content of Mg in the aluminumalloy is preferably in a range of not less than 7.5% and not more than9.0%, and more preferably in a range of not less than 7.5% and not morethan 8.5%.

[Ca]

Ca (Calcium) is present in the aluminum alloy mainly in the form of acompound. Even trace amounts of Ca cause cracking during hot working,and thus could lower workability. The content of Ca in the aluminumalloy being not more than 0.1% makes it possible to prevent crackingduring hot working. The content of Ca in the aluminum alloy is morepreferably not more than 0.05%.

(Elements Selectively Contained in Aluminum Alloy)

[Si]

Si (silicon) forms mainly second phase particles (for example, singleSi, Al—Si—Fe—Mn-based compound), and has an effect of making crystalgrains finer by acting as a nucleation site for recrystallization. Thecontent of Si in the aluminum alloy being not less than 0.02% makes itpossible to successfully obtain the effect of making crystal grainsfiner.

However, the content of Si in the aluminum alloy exceeding 0.3% causegeneration of a large amount of coarse second phase particles, and thuscould lower the elongation of a produced aluminum alloy material.Accordingly, the content of Si in the aluminum alloy is preferably in arange of not less than 0.02% and not more than 0.2%, and more preferablyin a range of not less than 0.02% and not more than 0.15%.

[Fe]

Fe (iron) is present mainly in the form of second phase particles (suchas an Al—Fe-based compound), has an effect of making crystal grainsfiner by acting as a nucleation site for recrystallization. The contentof Fe in the aluminum alloy being not less than 0.02% makes it possibleto obtain the effect of making crystal grains finer.

However, the content of Fe in the aluminum alloy exceeding 0.5% causesgeneration of a large amount of coarse second phase particles, and thuscould lower the elongation of a produced aluminum alloy material.Accordingly, the content of Fe in the aluminum alloy is preferably in arange of not less than 0.02% and not more than 0.25%, and morepreferably in a range of not less than 0.02% and not more than 0.2%.

[Cu]

Cu (copper) is present mainly in the form of a solid solution element,and has an effect of improving strength. The content of Cu in thealuminum alloy being not less than 0.05% makes it possible tosufficiently obtain the effect of improving strength.

However, the content of Cu in the aluminum alloy exceeding 1.0% causesoccurrence of cracking during hot rolling, and thus could lead todifficulty in production. Accordingly, the content of Cu in the aluminumalloy is preferably in a range of not less than 0.05% and not more than0.5%, and more preferably in a range of not less than 0.10% and not morethan 0.3%.

[Mn]

Mn (manganese) is present mainly in the form of second phase particles(an Al—Mn-based compound), and has an effect of making crystal grainsfiner by acting as a nucleation site for recrystallization.Specifically, the content of Mn in the aluminum alloy being not lessthan 0.05% makes it possible to sufficiently obtain the effect of makingcrystal grains finer.

However, the content of Mn in the aluminum alloy exceeding 1.0% causesgeneration of a large amount of coarse second phase particles, and thuslower the elongation of a produced aluminum alloy material. Accordingly,the content of Mn in the aluminum alloy is preferably in a range of notless than 0.1% and not more than 0.5%, and more preferably in a range ofnot less than 0.15% and not more than 0.3%.

[Cr, V, Zr]

Cr (chromium), V (vanadium), and Zr (zirconium) are present mainly inthe form of second phase particles (such as an Al—Fe—Mn-based compound,an Al—Cr-based compound, an Al—V-based compound, and an Al—Zr-basedcompound), and have an effect of making crystal grains finer by actingas a nucleation site for recrystallization. Specifically, the content ofCr or V in the aluminum alloy being not less than 0.05% or the contentof Zr in the aluminum alloy being not less than 0.02% makes it possibleto sufficiently obtain the effect of making crystal grains finer.

However, the content of Cr or V in the aluminum alloy exceeding 0.3%, orthe content of Zr exceeding 0.2% causes generation of a large amount ofcoarse second phase particles, and thus could lower the elongation of aproduced aluminum alloy material.

Accordingly, the content of Cr or V in the aluminum alloy is preferablynot more than 0.2%. In addition, the content of Zr in the aluminum alloyis preferably 0.1%.

The contents of Cr, V, and Zr in the aluminum alloy are not limited tothe above respective contents, provided that at least one of Cr, V, andZr is contained in the aluminum alloy.

[Ti]

Ti (titanium) inhibits the growth of a solidified phase of aluminumformed during casting and makes a cast structure finer, thus having aneffect of preventing a defect such as cracking during casting. However,an excessively high content of Ti in the aluminum alloy makes secondphase particles coarse, and thus could decrease the elongation of aproduced aluminum alloy material.

In light of the above, the content of Ti in the aluminum alloy being notmore than 0.2% makes it possible to prevent a decrease in the elongationof the produced aluminum alloy material. The content of Ti in thealuminum alloy is more preferably not more than 0.1%. Note thatsubstances other than the elements described above are basically Al andan inevitable impurity.

(Tensile Strength and Elongation)

The present embodiment enables production of an aluminum alloy material(H tempered material) having a tensile strength of not less than 300 MPaand less than 500 MPa and an elongation of not less than 20%, byperforming production treatments (which will be discussed later) on thealuminum alloy of the above composition. This makes it possible toprevent an end product from having poor strength due to the aluminumalloy having a tensile strength falling below 300 MPa. It is alsopossible to prevent the occurrence of a defect such as cracking duringworking on the end product due to the aluminum alloy having anelongation falling below 20%.

The tensile strength of the aluminum alloy material is more preferablynot less than 350 MPa. Further, the elongation of the aluminum alloymaterial is more preferably not less than 25%.

(Strength Anisotropy)

As illustrated in FIG. 1, an aluminum alloy material 1 of the presentembodiment is set such that, in a plane defined by a rolling direction(a final working direction) during a final rolling using a set of rolls2 and a transverse direction, a standard deviation of tensile strengthsis not more than 10 [MPa], wherein the tensile strengths are: a tensilestrength in a 0° direction forming an angle of 0° with the rollingdirection toward the transverse direction, a tensile strength in a 45°direction forming an angle of 45° with the rolling direction toward thetransverse direction, and a tensile strength in a 90° direction formingan angle of 90° with the rolling direction towards the transversedirection. This setting is made in consideration of the fact that thestandard deviation of the tensile strengths exceeding 10 [MPa], whichmeans an excessively high strength anisotropy, decreases the strength ina particular direction of an end product and could decrease thereliability of the end product. The standard deviation of the tensilestrengths is calculated by using Formula (1) (which will be describedlater).

The standard deviation of the tensile strengths of the aluminum alloymaterial 1 is preferably not more than 5 [MPa], and more preferably notmore than 3 [MPa].

(Crystallographic Texture)

The aluminum alloy material of the present embodiment is set to have a{013}<100> orientation density and a {011}<100> orientation densitywhich are calculated using a Crystallite Orientation DistributionFunction (ODF) and which are each not more than 5 (for example,approximately 1). This setting is made in consideration of the fact thatthe {013}<100> orientation density and the {011}<100> orientationdensity both exceeding 5 makes the strength anisotropy remarkable andthus could decrease the strength of an end product in a particulardirection.

In addition, the aluminum alloy material of the present embodiment isset to have a {123}<634> orientation density of not more than 5 and a{001}<100> orientation density of not more than 5. Such a setting ismade in consideration of the fact that the {123}<634> orientationdensity and the {001}<100> orientation density both exceeding 5 couldmake the strength anisotropy remarkable.

Now, a method for calculating an orientation density using thecrystallite orientation distribution function (ODF) will be described indetail. In the present embodiment, a three-dimensional orientationanalyzing method (see, Journal of Japan Institute of Light Metals, 1992,volume 42, No. 6, pp. 358 to 367) using the crystallite orientationdistribution function (ODF) is applied to a produced aluminum alloymaterial to calculate an orientation density. First, a cross section ofthe aluminum alloy material perpendicular to the working direction(rolling direction) is measured by an X-ray diffractometry. In thismeasurement, incomplete pole figures of (111), (220), and (200) planesare measured in an inclination angle range of 15 degrees to 90 degrees,using the Schlz reflection method (see, Journal of Japan Institute ofLight Metals, 1983, volume 33, No. 4, pp. 230 to 239). Next, thecrystallite orientation distribution function (ODF) is determinedthrough a series expansion. From this, an orientation density of eachorientation is calculated as a ratio with respect to the orientationdensity of a standard sample having random crystallographic texture.

(Method for Producing Aluminum Alloy Material)

The following description will discuss a method for producing thealuminum alloy material in accordance with the present embodiment. Themethod for producing the aluminum alloy material of the presentembodiment is carried out in the order of a casting step, ahomogenization step, a hot rolling step, a cold rolling step, and ananneal step. Steps of the production method are not limited to thesesteps, which are illustrated by way of example.

First, a slab is casted in the casting step by a semi-continuous castingprocess such as a Direct Chill (DC) casting process and a hot topprocess. The casting speed in the casting step is preferably 20 mm/minto 100 mm/min to prevent formation of coarse second phase particles.

Upon completion of the casting step, the homogenization step is carriedout. The treatment temperature is set to not less than 400° C. and notmore than 490° C. This is because (i) the treatment temperature beingnot more than 400° C. could cause insufficient homogenization, and (ii)the treatment temperature exceeding 490° C. could cause melting of anAl—Mg-based compound remaining without dissolving as a solid solution,and thus cause a defect such as cracking during the hot rolling.Further, coarsening of second phase particles excessively progresses,and crystal grains in a particular orientation tend to preferentiallygrow in the subsequent recrystallization process, so that the strengthanisotropy could decrease.

In the homogenization step of the present embodiment, a two-stagehomogenization treatment may be carried out. In that case, the treatmenttemperature for the first stage is set to not less than 400° C. and notmore than 450° C. This is because (i) the treatment temperature for thefirst stage being not more than 400° C. could cause insufficienthomogenization, and (ii) the treatment temperature for the first stageexceeding 450° C. could cause melting of an Al—Mg-based compoundremaining without dissolving as a solid solution, and thus cause adefect such as cracking during the hot rolling.

Further, the treatment time for the first stage is set to be in a rangeof not less than five hours and not more than 20 hours. This is because(i) the treatment time for the first stage being less than five hourscauses insufficient homogenization, and (ii) the treatment time for thefirst stage exceeding 20 hours causes decrease in productivity. Carryingout the homogenization treatment in the first stage with the treatmenttemperature and the treatment time being appropriately set as describedabove makes it possible to cause the Al—Mg-based compound to dissolve asa solid solution, and thus enables homogenization at a highertemperature.

Subsequently, the treatment temperature for the second stage is set tonot less than 450° C. and not more than 490° C. This is because (i) thetreatment temperature for the second stage being less than 450° C.causes insufficient homogenization, and (ii) the treatment temperaturefor the second stage exceeding 490° C. causes oxidization of Mg on thesurface to progress and thus could decrease concentration of Mg on thesurface.

Further, the treatment time for the second stage is set to be in a rangeof not less than five hours and not more than 20 hours. This is because(i) the treatment time for the second stage being less than five hourscauses insufficient homogenization, and (ii) the treatment time for thesecond stage exceeding 20 hours causes coarsening of second phaseparticles to excessively progress, causes crystal grains in a particularorientation to tend to preferentially grow in the subsequentrecrystallization process, and thus could decrease the strengthanisotropy.

Next, the hot rolling step is carried out. In the hot rolling step, thestarting temperature for the hot rolling is set to be in a range of notless than 350° C. and not more than 480° C. This is because (i) thetreatment temperature for the hot rolling being less than 350° C. couldmake the rolling difficult due to excessively high deformationresistance, and (ii) the treatment temperature for the hot rollingexceeding 480° C. causes the material to partially melt, and thus couldlead to the occurrence of cracking. Note that the hot rolling step maybe carried out with the homogenization step omitted.

Subsequently, upon completion of the hot rolling step, the cold rollingstep is carried out. In the cold rolling step, the cold rolling iscarried out such that a rolling reduction from the plate thickness atthe time of completion of the hot rolling step to the plate thickness atthe time of completion of the cold rolling step (a ratio of a platethickness after working to a plate thickness before the working) is notless than 50%. The rolling reduction only needs to be not less than 50%,and may be changed as appropriate.

Note that an intermediate annealing may be carried out before or in themiddle of the cold rolling step. In this case, the cold rolling is alsocarried out such that the rolling reduction from the plate thickness atthe time of completion of the intermediate annealing to the platethickness at the time of completion of the cold rolling is not less than50%. A treatment temperature for the intermediate annealing ispreferably in a range of not less than 300° C. and not more than 400° C.Further, a retention time for the intermediate annealing is preferablyin a range of not less than one hour and not more than 10 hours. This isbecause carrying out the intermediate annealing at a high temperaturefor a long time could cause deterioration in appearance quality due toprogression of oxidization on the surface.

Further, after completion of the cold working step, a final annealingstep is carried out. In the annealing step, an annealing temperature ispreferably not less than 300° C. and not more than 400° C., and aretention time is preferably not less than one hour and not more thanfive hours. The treatment temperature falling below 300° C. could causeinsufficient annealing effect. The treatment temperature exceeding 400°C. causes oxidization on the surface to progress and thus could causedeterioration in appearance quality.

According to the aluminum alloy material of the present embodimentdescribed above, it is possible to produce an aluminum alloy materialhaving both high strength and reduced strength anisotropy byappropriately controlling the metal structure through adjustments to thecomposition of the aluminum alloy and the production process for thealuminum alloy. This enables improvement in productivity of the aluminumalloy material and improvement in reliability of an end product.

EXAMPLES

The following description will discuss Example 1 of the presentembodiment with reference to Table 1 and Table 2.

(Composition of Aluminum Alloy)

Table 1 shows the composition of the aluminum alloy used in Example 1.

TABLE 1 Present Composition of Aluminum Alloy [% by Mass] Invention FeSi Cu Mn Mg Cr Ti V Zr Ca Al Example 1 0.22 0.10 <0.01 0.40 7.6 0.020.03 0.01 <0.01 <0.01 Remaining Percentage

As shown in Table 1, the composition of the aluminum alloy of Example 1is within a predetermined range. The predetermined range means that thecontent of Mg is in a range of 7.0% to 10.0%, and the content of Ca isin a range of not more than 0.1%.

(Production Method)

After the aluminum alloy having the composition shown in Table 1 ismolten and is subjected to the DC casting, the homogenization step, thehot rolling step, the cold rolling step, and the final annealing stepare carried out. The plate thickness of the aluminum alloy materialafter completion of the cold rolling step is assumed to be 1.0 mm.

In Example 1, heating at 465° C. for 12 hours is carried out in thehomogenization step prior to the hot rolling step. In the cold rollingstep, the rolling reduction from the plate thickness at the time ofcompletion of the hot rolling to the plate thickness at the time ofcompletion of the cold rolling is assumed to be 80%. In the finalannealing step, heating at 360° C. for two hours is carried out.

(Property of Aluminum Alloy Material)

Table 2 shows the strength property, the strength anisotropy, and theproductivity of an aluminum alloy material produced by performing theabove treatment on the aluminum alloy of Example 1 having thecomposition shown in Table 1.

TABLE 2 Tensile Strength {001}<100> {011}<100> {123}<634> {001}<100>Present Strength Elongation Anisotropy Orientation OrientationOrientation Orientation Invention [MPa] [%] [MPa] Density DensityDensity Density Productivity Example 1 364 32 1 G G G G G

(Tensile Strength and Elongation)

As shown in Table 2, the aluminum alloy material produced in Example 1has a tensile strength and an elongation within the respectivepredetermined ranges. In other words, the aluminum alloy materialproduced in Example 1 has a tensile strength of not less than 300 MPaand an elongation of not less than 20%.

Note that the tensile strength and the elongation of the producedaluminum alloy material are measured in conformity with JIS Z-2241-2011.As illustrated in FIG. 1, in a plane defined by a rolling directionalong which the set of rolls 2 moves (final working direction) and atransverse direction, tensile strengths and elongations of the producedaluminum alloy material 1 are measured in a 0° direction, which is therolling direction, in a 45° direction forming an angle of 45° with the0° direction from the rolling direction toward the transverse direction,and in a 90° direction forming an angle of 90° with the 0° directionfrom the rolling direction toward the transverse direction. The tensilestrength and the elongation of the produced aluminum alloy material 1are defined respectively as the average value for the measured tensilestrengths and the average value for the measured elongations.

(Strength Anisotropy)

Tensile strengths are measured, in the plane defined by the rollingdirection (final working direction) and the transverse direction, in the0° direction, which is the rolling direction, in the 45° directionforming an angle of 45° with the 0° direction from the rolling directiontoward the transverse direction, and in the 90° direction forming anangle of 90° with the 0° direction from the rolling direction toward thetransverse direction. The strength anisotropy is defined as a standarddeviation [MPa] calculated by using the following Formula (1).

$\;\begin{matrix}{{\sqrt{\frac{\sum\limits_{\text{?} = \text{?}}^{\text{?}}\left( {{TS}_{i} - {TS}} \right)^{2}}{\left( {n - 1} \right)}}\left( {n \geqq 2} \right)}{\text{?}\text{indicates text missing or illegible when filed}}} & {{Formula}\mspace{14mu}(1)}\end{matrix}$

In the formula, TS_(i) [MPa] represents a tensile strength of eachdirection, TS [MPa] represents the average value for the tensilestrengths in the respective directions, and n represents the totalnumber of pieces of the tensile strength data.

(Crystallographic Texture)

The three-dimensional orientation analyzing method using the crystalliteorientation distribution function (ODF) described above is applied tothe aluminum alloy material of Example 1 to calculate an orientationdensity. Specifically, a cross section of a portion of the producedaluminum alloy material in a plane perpendicular to the workingdirection (rolling direction) of the aluminum alloy material is measuredwith an X-ray diffractometry. In this measurement, after incomplete polefigures of the (111), (220), and (200) planes are measured using theabove Schlz reflection method in an inclination angle range of 15degrees to 90 degrees, a series expansion is performed to determine thecrystallite orientation distribution function (ODF).

The orientation density of each orientation thus obtained is calculatedas a ratio with respect to the orientation density of a standard samplehaving a random crystallographic texture. Table 2 shows results ofevaluations performed such that an aluminum alloy material having a{013}<100> orientation density of not more than 5 and a {011}<100>orientation density of not more than 5 is rated as “G (good)” and analuminum alloy material having a {013}<100> orientation densityexceeding 5 and a {011}<100> orientation density exceeding 5 is rated as“P (poor)”. Further, an aluminum alloy material having a {123}<634>orientation density of not more than 5 and a {001}<100> orientationdensity of not more than 5 is rated as “G”, and an aluminum alloymaterial having the {123}<634> orientation density exceeding 5 and the{001}<100> orientation density exceeding 5 is rated as “P”.

As shown in Table 2, it is understood that Example 1 successfullyreduced strength anisotropy. In addition, Example 1 shows the resultsthat indicate no problem with productivity.

COMPARATIVE EXAMPLES

As comparative examples to Example 1 described above, Table 4 showsproperties of aluminum alloy materials produced by performing atreatment similar to that for Example 1 on aluminum alloys ofComparative Example 1 to Comparative Example 4 having their respectivecompositions shown in Table 3. Note that, for Comparative Examples 1 and2, a treatment at 500° C. and for eight hours was performed as thehomogenization treatment.

TABLE 3 Comparative Composition of Aluminum Alloy [% by Mass] Example FeSi Cu Mn Mg Cr Ti V Zr Ca Al Comparative 0.16 0.07 0.08 <0.01 6.2 <0.010.01 <0.01 <0.01 <0.01 Remaining Example 1 Percentage Comparative 0.160.07 0.08 <0.01 5.7 <0.01 0.01 <0.01 <0.01 <0.01 Remaining Example 2Percentage Comparative 0.16 0.07 0.08 <0.01 11.0 <0.01 0.01 <0.01 <0.01<0.01 Remaining Example 3 Percentage Comparative 0.16 0.07 0.08 <0.019.0 <0.01 0.01 <0.01 <0.01 0.50 Remaining Example 4 Percentage

TABLE 4 Tensile Strength {001}<100> {011}<100> {123}<634> {001}<100>Present Strength Elongation Anisotropy Orientation OrientationOrientation Orientation Invention [MPa] [%] [MPa] Density DensityDensity Density Productivity Comparative 296 33 12 G G P P G Example 1Comparative 288 33 11 G G P P G Example 2 Comparative — — — — — — — PExample 3 Comparative — — — — — — — P Example 4

Comparative Example 1, in which the content of Mg is too low, results ina produced aluminum alloy material having a tensile strength fallingbelow the predetermined range, and thus fails to yield good mechanicalproperties. In addition, since the homogenization treatment temperatureis too high, the strength anisotropy exceeds the predetermined range, sothat Comparative Example 1 fails to yield good mechanical properties.

Comparative Example 2, in which the content of Mg is too low, results ina produced aluminum alloy material having a tensile strength fallingbelow the predetermined range, and thus fails to yield good mechanicalproperties. Further, since the homogenization treatment temperature istoo high, the strength anisotropy exceeds the predetermined range, sothat Comparative Example 2 fails to yield good mechanical properties.

Comparative Example 3, in which the content of Mg is too high, causesoccurrence of cracking during the hot rolling. This makes rollingdifficult, so that the production is impossible.

Comparative Example 4, in which the content of Ca is too high, causesoccurrence of cracking during the hot rolling. This makes rollingdifficult, so that the production is impossible.

The present invention is not limited to the embodiments, but can bealtered by a skilled person in the art within the scope of the claims.An embodiment based on a proper combination of technical means disclosedin different embodiments is encompassed in the technical scope of thepresent invention.

An aluminum alloy material in accordance with an aspect of the presentinvention contains Mg: 7.0% to 10.0% (% by mass, the same applieshereinafter) and Ca: not more than 0.1%, the aluminum alloy materialcontaining a remainder being constituted by aluminum and an inevitableimpurity, the aluminum alloy material having a tensile strength of notless than 300 MPa and less than 500 MPa and an elongation of not lessthan 20%.

The aluminum alloy material preferably contains Mn: 0.05% to 1.0%.

Further, the aluminum alloy material has a standard deviation of tensilestrengths of not more than 10, in a plane defined by a final workingdirection and a transverse direction of the aluminum alloy material,wherein the tensile strengths are a tensile strength in a 0° direction,which is the final working direction, a tensile strength in a 45°direction forming an angle of 45° with the 0° direction from the finalworking direction toward the transverse direction, and a tensilestrength in a 90° direction forming an angle of 90° with the 0°direction from the final working direction toward the transversedirection.

The aluminum alloy material preferably has a {013}<100> orientationdensity of not more than 5 and a {011}<100> orientation density of notmore than 5, wherein the {013}<100> orientation density and the{011}<100> orientation density are calculated using a crystalliteorientation distribution function (ODF).

The aluminum alloy material preferably has a {123}<634> orientationdensity of not more than 5 and a {001}<100> orientation density of notmore than 5, wherein the {123}<634> orientation density and the{001}<100> orientation density are calculated using a crystalliteorientation distribution function (ODF).

REFERENCE SIGNS LIST

-   -   1 aluminum alloy material    -   2 roll

1. An aluminum alloy material containing Mg: 7.0% to 10.0% (% by mass,the same applies hereinafter) and Ca: not more than 0.1%, the aluminumalloy material containing a remainder being constituted by aluminum andan inevitable impurity, the aluminum alloy material having a tensilestrength of not less than 300 MPa and less than 500 MPa and anelongation of not less than 20%.
 2. The aluminum alloy materialaccording to claim 1, wherein the aluminum alloy material contains Mn:0.05% to 1.0%.
 3. The aluminum alloy material according to claim 1,wherein the aluminum alloy material has a standard deviation of tensilestrengths of not more than 10, in a plane defined by a final workingdirection and a transverse direction of the aluminum alloy material,wherein the tensile strengths are a tensile strength in a 0° direction,which is the final working direction, a tensile strength in a 45°direction forming an angle of 45° with the 0° direction from the finalworking direction toward the transverse direction, and a tensilestrength in a 90° direction forming an angle of 90° with the 0°direction from the final working direction toward the transversedirection.
 4. The aluminum alloy material according to claim 3, whereinthe aluminum alloy material has a {013}<100> orientation density of notmore than 5 and a {011}<100> orientation density of not more than 5,wherein the {013}<100> orientation density and the {011}<100>orientation density are calculated using a crystallite orientationdistribution function (ODF).
 5. The aluminum alloy material according toclaim 3, wherein the aluminum alloy material has a {123}<634>orientation density of not more than 5 and a {001}<100> orientationdensity of not more than 5, wherein the {123}<634> orientation densityand the {001}<100> orientation density are calculated using acrystallite orientation distribution function (ODF).
 6. The aluminumalloy material according to claim 2, wherein the aluminum alloy materialhas a standard deviation of tensile strengths of not more than 10, in aplane defined by a final working direction and a transverse direction ofthe aluminum alloy material, wherein the tensile strengths are a tensilestrength in a 0° direction, which is the final working direction, atensile strength in a 45° direction forming an angle of 45° with the 0°direction from the final working direction toward the transversedirection, and a tensile strength in a 90° direction forming an angle of90° with the 0° direction from the final working direction toward thetransverse direction.
 7. The aluminum alloy material according to claim6, wherein the aluminum alloy material has a {013}<100> orientationdensity of not more than 5 and a {011}<100> orientation density of notmore than 5, wherein the {013}<100> orientation density and the{011}<100> orientation density are calculated using a crystalliteorientation distribution function (ODF).
 8. The aluminum alloy materialaccording to claim 4, wherein the aluminum alloy material has a{123}<634> orientation density of not more than 5 and a {001}<100>orientation density of not more than 5, wherein the {123}<634>orientation density and the {001}<100> orientation density arecalculated using a crystallite orientation distribution function (ODF).9. The aluminum alloy material according to claim 6, wherein thealuminum alloy material has a {123}<634> orientation density of not morethan 5 and a {001}<100> orientation density of not more than 5, whereinthe {123}<634> orientation density and the {001}<100> orientationdensity are calculated using a crystallite orientation distributionfunction (ODF).
 10. The aluminum alloy material according to claim 7,wherein the aluminum alloy material has a {123}<634> orientation densityof not more than 5 and a {001}<100> orientation density of not more than5, wherein the {123}<634> orientation density and the {001}<100>orientation density are calculated using a crystallite orientationdistribution function (ODF).